The present invention provides an improvement in communication networking by providing a high-speed routing mechanism for transmitting data between nodes on a communications network.
Conventional local area networks provide switches or bridges for linking users on a network. Switching systems in a communications network environment process requests from users to link a requesting user node with a destination node by decoding packets containing routing information generated by the requesting node.
Message switching is a form of data switching which relies on a store-and-forward technology. Each switch within a given network stores a network message in its entirety (packets) and transfers them out of storage upon the availability of the destination node. Often interrupt strategies are employed to achieve near real-time operation over portions of the network that are nearly transparent to the end users. Storage costs and complex interrupt handlers make these systems undesirable for low cost networks which seek to operate at or near real time with minimal system latency.
Circuit switching is a form of data switching which dedicates system resources to a particular call or transaction. Physical resources in time, space or frequency spectrum are dedicated to the exclusive use of a single call for the duration of that call. Circuit switching apparatus contain no storage devices, and merely route information based on the availability of a given destination node. Accordingly, "blocking" may result, wherein a call or transaction may not be established, due to the dedicated nature of the circuit switching connections whenever a system resource is in use.
Circuit switching systems operate in real time providing node to node communications once a connection is made between a source and destination. The performance of a circuit switching system can be measured in terms of connect time and latency. Connect time refers to the amount of time it takes to make a requested connection between a source and destination node in a network. Latency is a related consideration which refers to the time period between the application of a stimulus (a request for connection in a network) and the first indication of a response from the network. Most network communications are inherently short duration in nature, on the order of magnitude of 5 milliseconds or less. Accordingly, networks employing circuit switching systems are required to rapidly connect and disconnect physical resources as fast as possible to avoid "blocking" of transactions, and achieve transparent real time communications on the network. Any improvements in speeding up the connect and disconnect cycles as well as improving the overall system latency is desirable in networks employing circuit switching.